Global variables not changing

[snippsat]

This is just confusing and there most be better way than to solve whatever you try to do.
To fix it,you never call function met1 and met3 function and there is no return or print().
Never use global,don't ask why

import tst2

tmp = None
def main():
    print(tmp)
    print(met1())
    print(tmp)

def met1():
    return tst2.met2()

def met3():
    tmp = 5
    return tmp

if __name__ == "__main__":
    main()
    print(met3())
    print(met1())

import tst1

def met2():
    return tst1.met3()

Output:
None
5
None
5
5

Still